Over the last decade, thanks to high-resolution observations of galactic nuclei by the Hubble Space Telescope (HST), supermassive black holes (SBHs) have been detected in two dozen or so galaxies (including the Milky Way). These detections rely on the measurement of the appreciable dynamical effects that a black hole exerts on nearby gas and stars.
Dr. Touma will conduct a detailed study of stellar dynamics around SBHs in galactic nuclei. This study will bolster detection efforts through careful dynamical modeling of kinematic observations. It will also help to clarify the role that a SBHs play in shaping features found in the central regions of the host galaxy. Finally, it will shed some light on questions relating to the origin and evolution of SBHs. In particular, it will involve a thorough analysis of a violent instability that Dr. Touma has recently identified. This instability affects stellar disks which are dominated by a SBH in their center, and which harbor a small proportion of counter-rotating stars. The instability distorts the disk into a lopsided shape and promises to explain the lopsided nucleus of the Andromeda Galaxy (M31), which harbors an SBH, and is suspected of supporting a small percentage of counter-rotating stars. ***
